Joint-forming device



s- 2, 1969 D. 0. BROWN 3,460,796

JOINT-FORMING DEVICE Filed D60. 9, 1966 lNl/EA/TUR. DEL MO/VT 0. BROWN United States Patent Olhce 3,460,796 Patented Aug. 12, 1969 3,460,796 JOINT-FORMING DEVICE Delmont D. Brown, North Baltimore, Ohio, assignor to The D. S. Brown Company, North Baltimore, Ohio, a corporation of Ohio Filed Dec. 9, 1966, Ser. No. 600,448 Int. Cl. B01c 11/02 U.S. Cl. 249--9 2 Claims ABSTRACT OF THE DISCLOSURE Joint-forming tool for concrete pavements adapted to be pushed into wet concrete at ends of transverse pavement joints to form vertical slots or grooves adjacent concrete-retaining forms or rails and embodying molded thermoplastic polymer body having slot-forming bar with diagonal 'lower corner on front edge and relatively flat foot member, preferably having a beveled upper face, extending laterally from the upper portion of the rear edge of said bar.

This invention in general relates to a joint-forming device adapted to be driven or pushed into poured concrete at the ends of a transverse slot or groove such as a concrete contraction joint in concrete pavement, or at positions wherein such joint is to be sawed in concrete after the initial set thereof, to provide downwardly depending extensions of the transverse slot or groove. Such downward extensions constitute vertical slots or grooves at opposite ends of the concrete joint adapted to receive the downwardly bent ends of an elastomer joint seal inserted in the joint in a laterally compressed state. This arrangement of the elastomer seal protects the joint against intrusion of water, dirt or other incompressible solids downwardly into the joint and also laterally into the ends of the joint.

In recent years, hollow, elongated, elastomer strips have been developed for use as seals in concrete joints such as expansion and contraction joints in concrete roadways, air strips, and the like. These joint seals are inserted in a laterally compressed state into the joints to seal them against intrusion by water, solids and the like. The sides of the joint seal strips are in tight, sealing contact with the side walls of the slots or grooves forming the joint.

Joints of the aforesaid character are used in concrete pavement or similar concrete structures to permit expansion and contraction of a given length of the concrete under varying temperature conditions. These joints, which extend transversely across roadways at predetermined intervals, are wide enough to accommodate the lineal expansion of a pavement under warmer climate conditions, and to control random cracking by creating a line of weakness. The joints are usually formed by a spacer member which is inserted between adjacent pavement sections before the sections are poured, or by sawing a transverse groove in a continuous strip of pavement, usually after the concrete has initially set.

The joint-forming device may be used in connection with contraction joints which are formed crosswise of a pavement strip or highway at less than the full depth of the slab, the groves of which joints are usually about one-fourth the depth of the slab, e.g., about two inches deep. The important function of such contraction joints is to prevent irregular breaking of the pavement during contraction of the pavement since such irregular breaks are difiicult to repair. The grooves for contraction joints serve mainly the purpose of providing lines of weakness extending crosswise of the pavement.

These joints must be sealed in order to prevent accumulation of unwanted particles such as sand or grave], or other incompressibles from entering the open joint, filling this space and preventing the slab from expanding and closing the joint opening. Joints are also sealed to prevent infiltration of water, which in cold weather would lead to heaving and cracking of the pavement adjacent the joint or in summer allow the subgrade to erode. It has been standard practice for many years to fill such grooves with an asphalt r0 similar type of filler which would yield during warm weather when the width of the joint becomes smaller due to expansion of the adjacent pavement lengths. Joints having such filling materials must be repaired and replaced periodically and normally require inspection and repairs at six month intervals.

The joint former of the invention preferably comprises a unitary moulding of thermoplastic polymer such as polyether or polyesters or polyurethanes as the type described in U.S. Patent No. 3,237,777, or the like, or any other mouldable thermoplastic having a high modulus impact resistance such as 66 or 610 nylon, polylactams, or like polyaimides, polyvinyl chloride, high impact polystyrene, and polypropylene. This joint former comprises a rectangular slot-forming bar with a diagonal lower corner and adapted to be driven into the wet concrete at the aforementioned places in a concrete slab adjacent the outer edges thereof. The joint former includes a foot member extending at right angles from the upper end of the slot-forming bar and projecting laterally from the side of the bar opposite to that in which the diagonal corner is positioned. The foot member is adapted to rest on the upper surface of a rail or other form member which is used to retain and form the longitudinal edges of the poured concrete slab.

A preferred form of the invention is illustrated in the drawing, wherein:

FIG. 1 is a fragmentary, sectional view in a section plane extending transversely across a concrete slab through the transverse concrete contraction joint in the upper surface thereof with joint formers inserted at opposite ends of the concrete joint against side form rails extending longitudinally along the edges of said slab;

FIG. 2 is a top plan view, in fragment, of the concrete joint and the elements illustrated in FIG. 1;

FIG. 3 is a transverse section similar to the section taken in FIG. 1 after the joint formers and side rails have been removed and an elongated, laterally compressible, elastomer sealing strip has been inserted in the concrete joint; and

FIGS. 4, 5 and 6 are, respectively, a. rear elevation, side elevation, and top plan view of the joint former of the invention.

Referring to the drawings, a poured concrete slab or strip 10, such as a poured slab or strip for roadways, air strips, or the like, is poured between form members, i.e., the side rails 11 and 12. The latter are of known construction and use and are employed both for the purpose of retaining and forming the longitudinal edges of the poured concrete slab, and for supporting and guiding concrete laying and finishing machinery which travel along the rails to pour and finish the concrete slab.

At regular intervals the concrete slab is provided with a transverse slot or groove 13 to provide contraction joints of the aforedescribed nature. Such groove is ordinarily considerably less than the full depth of the concrete slab.

A slot or groove forming the concrete joint may be formed in the wet concrete immediately after pouring and/or finishing, or it may be sawed in the concrete after the initial set thereof. Techniques, tools and machines for forming such joints are known in the art.

The joint former 15 of the invention comprises a vertical, slot-forming bar 16 of generally rectangular configuration. It has a diagonal corner 17 at the lower end of the front edge, which edge faces away from the side rails 11 and 12. This slot-forming bar is pushed or driven into wet concrete. The diagonal corner 17 acts as a wedging edge which pushes and retains the opposite rear edge 14 of the bar 15 against the inner face of the side rails 11 and 12 as the slot-forming bar is driven into the wet concrete.

A relatively flat foot member 18 is moulded integrally with and extends laterally from the rear edge 14 of the bar 16 at the upper portion thereof. The flat, lower face 19 of the foot member 18 is preferably rectangular and lies in a plane substantially at right angles through a plane through the edge 14. The lower face 19 rests on the upper sides 20 and 21 of rails 11 and 12 when the joint former 15 is driven to its full depth into the concrete.

The upper face of the foot member 18 preferably comprises outwardly beveled sections 22, 23 and 24 providing bevels toward the respective ends 31 and 32 and the side 33 opposite the bar 16 of said foot member. Said beveled sections extend outwardly from a relatively thick base portion 25 having sufficient thickness to assure substantial rigidity between the foot member 18 and the slot-forming bar 16 at the juncture thereof. The bar 16 intersects the lower face 19 at about the mid-portion of side 34.

The beveled portions are provided so that the wheel of any machine or tool traveling along the side rail 11 and 12 after pouring of the concrete and insertion of the joint formers 15 will pass over the foot members 18 without difficulty.

After the concrete has at least initially set, the joint formers 15 and side rails 11 and 12 are removed, leaving the poured slab. If the joint is formed in the wet concrete it will comprise a transverse slot or groove 13 with downwardly extending grooves 26 and 27 at opposite ends of the grooves 13. If the transverse slot or groove 13 is to be sawed after initially set in the concrete, it is sawed in the concrete so that it intersects the downwardly depending slots 26 and 27, which result upon removal of the joint formers 15.

An elongated, laterally compressible, elastomer sealing strip 28 is inserted at a later date to form a watertight and solids-tight seal. Such elongated seals are known in the art and are disclosed, for example, in United States Patent No. 3,179,026. The elongated elastomer seal is mounted in the slotted groove 13 with end portions 29 and 30 extending sufficiently beyond the ends of the slot or groove 13 so that the end portions can be turned downwardly and forced in a laterally compressed state into the downwardly depending slots 26 and 27, thereby forming a water-tight and solids-tight seal, not only along the transverse slot 13, but also in the side edges of the concrete slab 10 at opposite ends of the slot or groove 13.

It is thought that the invention and its numerous attendant advantages will be fully understod from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. A joint-forming device useful in forming vertical slots in poured concrete at opposite ends of a transverse groove in a concrete slab, said device comprising a vertical, slot-forming bar of generally rectangular configuration with a front edge having diagonal, lower corner, said diagonal corner providing a wedging edge, a relatively fiat foot member extending laterally from the upper portion of the rear edge of said bar and having a fiat, lower face adapted to rest on the top edge of a concrete form extending along the side of said slab, said lower face being rectangular, said rear edge intersecting the mid-portion of a side of said rectangle at substantially right angles thereto, a relatively thick base portion of said foot member joining the upper portion of said bar and said foot member, and the upper face of said foot member having beveled sections extending from said base portion toward the respective ends of said foot member.

2. A joint-forming device as claimed in claim 1, said bar and said foot member being an integral moulding of a synthetic polymer.

References Cited UNITED STATES PATENTS 1,629,544 5/1927 Shaw 9451 X 1,976,396 10/1934 Holcomb 945l 3,300,920 l/l967 Skaare 2493 X J. SPENCER OVERHOLSER, Primary Examiner JOHN S. BROWN, Assistant Examiner US. Cl. X.R. 

